Income tax provisions affect the buildup of retirement assets during workers’ careers and after-tax income following retirement.  This paper uses the Urban Institute’s DYNASIM model to simulate how potential changes in the tax treatment of retirement saving, Social Security benefits, and income from assets outside of retirement accounts may affect boomers’ retirement incomes.  Results show that changes in the income thresholds for taxing Social Security benefits have the largest impact on middle-income boomers, while changes in contribution limits for retirement saving plans and tax rates on capital gains and dividends have the largest impact on the highest income boomers.